1. Field of the Invention
The present invention relates to inflatable escape slides and inflatable slide rafts for use by passengers evacuating aircraft. The slides are environmentally sealed under a vacuum to reduce the overall bulk of the stored slide and to extend the slide's repack interval and overall useful life.
2. Background
Inflatable escape slides are installed in virtually all large passenger-carrying aircraft to provide a rapid means for evacuating passengers in the event of an emergency. Such inflatable escape slides typically include at least one inflatable structural beam member. The slide surface (for use by the evacuating passengers) is provided on the upper side of the structural beam member. The structural beam member is inflated using compressed gas and an aspirator and/or a turbo fan. The upper end of the structural beam member is connected to the bottom of the aircraft's doorway by a girt bar assembly. Prior art inflatable escape slides are disclosed, for example, in U.S. Pat. Nos. 2,765,131, 3,102,623, and 3,860,984.
These inflatable escape slides are normally folded and packed so that they require only a minimal amount of space within the interior of the aircraft. They are typically mounted on the interior of the aircraft door, or immediately adjacent thereto. When the door is closed, the slide is manually connected to brackets on the floor inside the doorway using a girt bar. In the event of an emergency, it is only necessary to open the door so that the girt bar pulls the slide from the package as the door opens, thereby allowing the slide to fall through the doorway. The slide is then inflated and is ready for passenger evacuation.
It is important to minimize the overall dimensions of the packed escape slide. The packed escape slide must be small enough to reliably deploy through the aircraft door when activated. Also, it must not interfere with the normal operation of the door, or with the use of the door by passengers exiting the aircraft.
The packing procedure for inflatable escape slides is generally both time-consuming and labor-intensive. It may require as many as three or four persons. The escape slide is folded in a sequence which will allow reliable inflation and deployment. The folded escape slide is then placed into a relatively shallow receptacle commonly called a packboard. A series of fabric panels, which are attached to the periphery of the packboard are then laced together with cord to contain the folded escape slide between the packboard and the fabric panels. The packed escape slide is then compressed to the desired configuration by manually pressing down the surfaces of the packed assembly and tightening the laces. Alteratively, a vacuum line is applied to the inflatable member(s) of the slide, and the packboard laces are tightened.
Several problems arise with these procedures. First, the inflatable members of the escape slides might be damaged during both the preliminary folding operation and the subsequent compression of the slide. The inflatable members are generally fabricated from a neoprene rubber-coated fabric that may be punctured or torn by hard-surfaced apparatus such as lighting fixtures, survival equipment, inflation devices, or compressed gas reservoirs that are packaged with the escape slide.
Second, compact packaging of the inflatable escape slides is becoming increasingly difficult to achieve due to longer slide lengths (which have been necessary to service wide-bodied aircraft), double-wide slides (which can evacuate 2 streams of people) and the inclusion of more accessories in the slide pack, such as lights, inflatable rafts, and other survival equipment. Compact packaging is especially difficult to achieve in the case of the slide/raft escape units which serve as both slides and life rafts. Slide/rafts are more difficult to pack because they are generally bulkier than standard escape slides, and they include a wide variety of survival and rescue equipment. For example, slide/raft packs can include radio beacons, locator lights and their associated batteries, antennae, hand pumps, anchors, heaving lines, knives, and canopies.
Third, inflatable escape slides have a limited useful service life of about 15 years. During this time, typical escape slides must be inspected at least three times. Inspection usually includes deploying the slide, inspecting it, and repacking it. The service life of a typical inflatable escape slide is affected by (1) the wear due to the inspection and repack cycle, (2) deterioration due to exposures to an atmosphere that may contain corrosive gases, eg., jet fuel, hydraulic fuel vapors, engine exhaust, and (3) aging of the escape slide materials due to fungus growth, moisture, oxygen, ozone, smog, ultraviolet light, high temperature/low temperature cycling, and aircraft vibration.